The share of Natick’s eligible population fully vaccinated against COVID-19 has crept up fron 85% to nearly 86%, with the 20-29 age category now up to 70%, according to weekly data released by the state. Statewide, COVID-19 numbers have started to creep up, as the highly contagious Delta variant of the virus infects people, mainly those who are unvaccinated.

Now 74% of Natick’s population has been fully vaccinated, but that includes those under the age of 12 who are not eligible for COVID-19 vaccinations.

Just over 26,500 of about 31,000 Natick residents eligible for the vaccine have now been fully vaccinated, and the state has surpassed 4.4 million fully vaccinated against the disease. About 100 Natick residents joined the ranks of fully vaccinated over the past week.

Natick is nearing 93% of its overall eligible population with at least 1 dose. State data shows the percentage of 12-15-year-olds fully vaccinated has risen from 75% to 78% over the past 2 weeks—that’s a relatively big jump this far into the process. No other age category has seen more than a 1% increase. Those in the 20-29 age range still have the most catching up to do, stuck at 70%—though 78% have now had at least 1 dose.

There are theories as to why this age category is behind, including that college students may have been vaccinated partially in Massachusetts and partially elsewhere or entirely in another state, and that the numbers haven’t been tallied the same as for other categories. There’s also concern nationally that this age group may not feel it’s at as much risk from COVID-19, and they’re not as influenced by parents to get shots as teens would be.